There are existing methods and devices for thermal control in one or more components of a spacecraft. Some of these methods and devices utilize heat pipes such as constant conductance heat pipe, and variable conductance heat pipe in order to maintain thermal control. Other methods and devices utilize thermal control surfaces such as mirrors, paints, coatings, and multi-layer insulation blankets. Still other methods and devices utilize heaters, mechanical louvers, and phase change materials.
These thermal control tools may be grouped into local or electronic-level control, and subsystem or spacecraft-level control. For instance, phase change materials may be used at the electronic-level, and constant conductance heat pipe may be used to spread the heat of the electronics. The rest of the methods and devices referred to may be considered subsystem or spacecraft-level control.
Thermal radiators made from mirrors, and thermal paints or coatings may be sized to reject heat, but may require heaters to maintain minimum temperature during cold periods or inactive times. Many commercial satellite allocate between 400 to 500 watts for heater power to maintain electronics above minimum operating temperatures. Multi-layer thermal blankets may be used to isolate and/or to minimize heat loss. Satellite thermal control may utilize a combination of all of these thermal control tools.
Mechanical louvers usually are not used in satellite thermal control due to reliability, operational limitation, and weight issues. Variable conductance heat pipe may use temperature-activated thermal control. However, there may be power issues, weight costs, and/or increased system design complexity as the variable conductance heat assembly may require heating and cooling for its condensers to control the pipe's conductance.
A thermal control device or method is needed which may solve one or more problems in one or more of the existing methods and/or devices for controlling thermal conditions.